1. FIELD OF THE INVENTION
This invention relates to an alarm circuit in a horological device and, more particularly, to a novel alarm switch for operating the alarm circuit.
2. DESCRIPTION OF THE PRIOR ART
Alarm clocks and wristwatches having an alarm circuit for generating an audible alarm signal at a predetermined time are well known in the prior art. Relatively large dimensioned and cumbersome mechanisms employing cams or mandrels for actuating or adjusting switch contacts are generally used in a switch assembly for the alarm circuit. An attempt to simplify and provide an alarm circuit construction of small dimensions is described in U.S. Pat. No. 3,774,967 entitled "Watch With Adjustable Time-Dependent Signal Transmission," issued to Paolo Spadini on Dec. 4, 1973. Contact arms on an hour recording wheel and an adjustment indicator engage selected conductive surfaces on an integrated circuit arranged to activate a signal generator at a very large number of signal time points. It is understood that the integrated circuit could dissipate energy from a power source, such as a battery, even when the signal generator is not activated. Thus, it is desirable to provide a switch assembly construction of small dimensions that will conserve electrical energy until the signal generator is activated at a predetermined time.
U.S. Pat. No. 3,611,702 entitled "Electric Alarm Timepiece" issued to Paolo Spadini on Oct. 12, 1971 describes an electric switch including a first switch contact mounted to turn with an hour wheel. A second switch contact is included in a contact wheel comprising two parts; a metal hub and an electrically insulating plastic disc which partly covers an annular lip of the hub. The hour wheel and contact wheel are coaxially mounted on a cannon-pinion pipe so that the first switch contact on the hour wheel may slide over the plastic disc to eventually touch the second switch contact at a predetermined time.
The design and construction of switches of this kind for horological devices require a relatively thick alarm or contact wheel which could be susceptible to angular displacement when subjected to mechanical shock and vibration. Accordingly it is desirable to provide a switch assembly including a relatively thin alarm wheel that is easily fabricated and less susceptible to mechanical shock and vibration than prior art electric switches.